*3.2. ES Supply and Demand Change and Mismatches*

#### 3.2.1. Water Yield Service

Over the entire period, the total water yield service supply exceeded demand, with surpluses of 47.72 billion m3, 60.31 billion m3, and 41.88 billion m3 in 2000, 2010, and 2018, respectively (Table 2). Water yield service supply in 2000, 2010, and 2018 was 72.32 billion m3, 84.63 billion m3, and 66.90 billion m3, respectively, showing a trend of increase followed by a decrease. The water demand increased significantly from 24.60 billion m3 in 2000 to 25.02 billion m<sup>3</sup> in 2018, an increase of 1.69%.

Water yield service supply was strongly influenced by precipitation and evapotranspiration, while water demand was influenced by population density and industrial structure. Precipitation anomalies can increase the uncertainty of the spatial match of water yield service. Although there was an overall surplus of water service, the spatial distribution of water yield service supply and demand also showed a mismatch (Figure 4). The southern and eastern parts of the study area were the main areas of water yield service supply

(Figure 5), but the deficit situation of the water yield service was still significant due to the dense population and agricultural development of the area, which means that there is a huge demand for water resources. Due to the lower water yield service supply in 2018, this has resulted in a significant deficit in water yield service in the South East, with the shortfall areas mainly in the city center.

**Figure 4.** Spatial pattern of supply and demand for individual ecosystem services (ES) in the Yellow River Basin in 2000, 2008, and 2018. ES indicators are: WY—water yield; CS—carbon sequestration; SC—soil conservation; GP—grain production.

**Figure 5.** Spatial pattern of the ecosystem service supply-demand ratio in the Yellow River Basin in 2000, 2008, and 2018.

#### 3.2.2. Carbon Sequestration Service

Carbon sequestration service supply has shown an increasing trend, from 134.45 million tons in 2000 to 235.76 million tons in 2018, an increase of 75.35% (Table 2). However, the growth in the carbon sequestration service supply did not cause surpluses. Carbon sequestration demand in 2000, 2010, and 2018 was 134.45 million tons, 210.75 million tons, and 235.76 million tons, respectively, and the carbon sequestration demand in 2010 and

2018 exceeded the carbon sequestration supply with a deficit of 29.66 million tons and 49.48 million tons, respectively, with an upward trend.


**Table 2.** Ecosystem services supply and demand in the Yellow River Basin in 2000, 2010, and 2018.

According to the spatial distribution of carbon sequestration service supply and demand (Figure 4), higher carbon sequestration service supply was mainly concentrated in the south, showing an increasing trend, followed by a decreasing trend. Carbon sequestration supply in the north-western region was relatively low and shows an increasing trend. Higher carbon sequestration service demand was mainly in the main urban area downstream of the study but showed a decreasing trend from 2000 to 2018. There was a clear spatial mismatch in sequestration service (Figure 5), with increased surpluses in the central and western regions of the study area and relatively significant deficits in the eastern regions. The main urban areas around the study area showed a significant deficit in carbon sequestration service, with Zhengzhou showing an increase in the deficit position in 2018.
